Telephone system.



fNo. 796,441. PATBNTED AUG.'8, 1905.

K. B. MILLER.

TELEPHONE SYSTEM.

APPLICATION rum) PEB. 4. 1901.

UNITED STATES PATENT OFFICE.

KEMPSTER B. MILLER, OF CHICAGO, ILLINOIS, ASSIGNOR TO KELLOGGSWITCHBOARD AND SUPPLY COMPANY, OF CHICAGO, ILLINOIS, A

CORPORATION OF ILLINOIS.

TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Aug. 8, 1905.

Application filed February 4., 1901. Serial No. 45,928.

T0 all whom it nfl/ty con/cern.-

Beit known that I, KEMPSTER B. MILLER, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented a certain new and useful Improvement in Telephone Systems, ofwhich the following is a full, clear, concise, and eX- act description,reference being had to the accompanying drawings, forming a part of thisspecification.

My invention relates to a central-energy telephone system, my objectbeing to provide an improved form of signal apparatus at the centralstation.

In accordance with my invention I provide a repeating-coil through whichthe telephonelines are adapted to be united for conversation, thecharging source of electricity and the windings of thesignal-controlling electromagnet being placed in a bridge between thetwo limbs of the talking-circuit.

The present invention contemplates means for preventing the chargingsource of electricity from becoming short-circuited through the windingsof the repeating-coil, and to this end I preferably interpose acondenser in the bridge containing the windings of the repeating-coil,although the present invention contemplates any means for opening thecircuit through the windings of the repeating-coil to prevent thepassage therethrough of the current from the charging source.

Ihave illustrated my invention in the accompanying drawings, in which-Figure l is a diagram illustrating two telephone-lines and thecentral-station apparatus for uniting the same for conversation. Fig. 2is a diagram showing the talking-circuits of two connected subscribers.Fig. 3 is a view of a modification in which the condenser is placed uponone side of the windings of the repeating-coil. Fig. L is amodication inwhich a single condenser is employed for both windings of therepeating-coil.

Like characters refer to like parts in the several figures.

The telephone-line A extends in two limbs a a' at the central station,where said limbs terminate, respectively, in the springs a2 a3, thespring a2 normal'ly resting against back contact 1, which is connectedto ground, the spring a3 normally resting against back contactZ, whichis connected, through individual annunciator c, to conductor 3. Thesprings a2 a3 carry armatures resting opposite the poles of arelay-magnet b, and the spring a2 when attracted is adapted to engagefront contact 4, which is connected with the linesprings d d of thespring-jacks or switchsockets d d. The spring a3 is adapted whenattracted to engage contact 5, which is connected with the sleeves Z2 d2of the springjacks. Moving with spring a3, but insulated therefrom, is aspring a, connected to ground through resistance a5 and adapted when therelay is energized to engage contact 6, which is connected with thetest-rings (Z5 d5. One end of the winding of relay b is connected withconductor 3 and the other end is connected with the contact-springs Z3da, which springs are mounted to move with but insulated from theline-springs d cZ, respecthereof to carry the spring dsinto engage-vment with the grounded contact d4.

The subscriber is provided at the 'substation' with the usual microphonef, receiver f and switch-hook f2, normally resting out of engagementwith contact 8. The bell f3 and a condenser Z3 are connected between thetwo limbs a a. When the telephone is removed from the hook, the hookengages contact 8, which is connected with the telephone transmitter andreceiver.

The telephone-line B shown at the right of the drawings is like thetelephone-line A and is provided with the same parts and mechanism, andlike parts have been indicated by the same reference characters employedin connection with the line A.

T he answering-plu-g p is provided with a tip p and a sleeve p2, theformer being connected with the'strand t and the latter with a strand s.The calling-plug 0 is provided with a tip 0 and a sleeve 02, the formerbeing connected with a strand t and the latter with a strand s. Thestrands s and t s are united through a repeating-coil w, having windingsw and yw2 connected between the strands t and e and windings w3 and w*connected between the windings and s. f In circuit with windings w andQ02 is a condenser Z, and in circuit with windings w3 w4t is a condenserZ. Be-

tween the strands tand s the windings It and if of a relay 7L areprovided, a battery .r being interposed between said windings. Likewisebetween the strands t' and s the windings i' and 702 of relay 7c areconnected, the battery r being interposed between said windings. Thewindings of the relays are in such a direction that the same assist eachother in magnetizing the core. The conductors 3, eX- tending to thetelephone-lines, are connected some with the battery r and somewithbattery r', and the opposite poles of said batteries are grounded.Opposite the pole of relay ta spring m is provided carrying an armatureand 'adapted when the relay is denergized to engage. contact 13. Contact13 is connected, through the lamp m', with one pole of the battery r andthe spring m is connected with tlie"'opposite pole of said battery.Likewise the spring e of relay 7f3 is connected with onepole of batteryr and the contact 15 is connected, through lamp c, to the opposite poleof said battery. rlhe contacts m2 and 14: of a plug-seatswitch-controlled by plugp are interposed'in the circuit of the lamp m.Likewise the contacts c2 and 16 of a plug-seat switch-controlled by plug0 are interposed in the .circuit of the lamp e.

In the strands t and s the levers g g of the ringing-key are provided,said levers normally resting against contacts 17 17 and adapted whendepressed to engage contacts 18 18, between which the generator g isconnected. The operators telephone set z' is adapted to be connectedbetween the strands t and s', anda condenser 12 is interposed in thecircuit of the telephone set.

Assuming now that subscriber A is desirous of conversing with subscriberB, he lifts his receiver from the telephone-hook, thereby closingtogether limbs rt a' at the substation. The circuitof battery r is thusclosed over conductor 3, annunciator c, contact 2, spring a, limbs a, aspring c2, contact 1 to the opposite pole of battery r. The individualannunciator c is thus actuated to convey to the operator. the signal forconnection, and the operator thereupon lifts the answering-plug p andinserts the same in the spring-jack belonging to subscriber A. Theinsertion of the plug moves spring Z3 against contact cli, therebyenergizing the relay the circuit through said relay being traced frombattery r, through conductor 3, relay I), spring d3, contact d* toground and back to the battery. The relay being thus energized attractsthe armatures and moves springs a2 o3 out of engagement, respectively,with contacts 1 and 2, thus disconnecting the annunciator from circuit,and moves said springs into engagement, respectively, with contacts 4and 5, thus connecting the terminals of the spring-jacks with the limbsof the telephone-line. The insertion of the answering-plug also connectsbattery fr in circuit through the windings it h2 of relay t and throughthe strands t and s of the cord-circuit and the limbs a rt of the line.The removal of the answering-plug from its seat closes the circuitthrough lamp m', thereby lighting the same. The insertion of the plug inthe spring-jack closes circuit through the two windings of the relay,thereby energizing the same and opening the lamp-circuit at the contactsm and 13. The operator then connects her telephone set e' infcircuit inthe usual manner and receives the number of the called subscriber.Learning that connection is desired with subscriber B, she lifts theanswering-plug 0 and touches the tip 0 thereof to the test-ring (Z5,belonging to the springjack of subscriber B. 1f subscriber B is busy,his relay will be` energized and test-ring Z5 will be connected toground through contact 6 and spring rf. If the line be thus busy, theoperator upon touching the tip of plug 0 to the test-ring will hear aclick in her telephonereceiver; but, on the other hand, if the line beidle she will hear no click and will know that the line is not busy. Theclick in the vtelephone is due to the fact that by touching the tip ofthe plug to the line-contact the potential at the point t2 of strand islowered. thereby permitting a current to flow through the operatorsreceiver. When the tip 0 is not in contact with the test-ring, thebattery r' is on open circuit and the point t2 is therefore of the samepotential as the pole of the battery. When, however, the tip of the plugis touched to the test-ring, the circuit of battery r is closed fromground through the winding In', strand t', tip 0', testring d5, contacts6 and to ground. The resistance thus interposed between the pole of thcbattery and the point t2 by the winding c lowers the potential of thepoint t2 on closed circuit,

and this change of potential of the point t2, with which the operatorstelephone set is connected, causes a momentary current to flow throughthe receiver, thereby causing a click therein.

Assuming that the operator finds the line of the called subscriber idle,she inserts the plug 0 in the spring-jack thereof and then depresses theringing-key g', thereby sending current from generator g over strands ts and limbs a a' through the bell at the substation. Wvhen thesubscriber responds, he lifts the receiver from the hook, thus closingtogether the limbs a a at the substation. The circuit of battery r isthus closed through windings c L2, strands t s', and limbs a a. When thecalling-plug0is removed from its seat,the circuit through lamp fu isclosed and the lamp is lighted. When the called subscriber removeshis'telephone from the hook, current traverses the windings of the relaybelonging to the called subscriber and the circuit through the lamp isthus opened at the contacts/u and 15. rlhe circuits during conversationare shown in Fig. 2. When the subscriber A is talking and the microphoneis actuated, variation of the resistance thereiny causes a correspondingvariation of the difference of potential between the points m and w, andthis variation of difference of potential causes acorrespondingly-varying current to traverse the windings w and wz,thereby inducing' corresponding currents in windings 'w3 and 104, whichpass through the receiver of subscriber B. Likewise when subscriber B istalking the diiference of potential between the points 1/ and y isvaried and correspondingly-varying currents will be ycaused to passthrough the receiver of subscriber B.

/Vhen the subscribers have completed their conversation and desiredisconnection, they hang up their telephone-receivers, thereby openingthe circuit of the batteries through the relays. The relay-contacts arethus closed together to permit the lighting of the lamp. Thus whensubscriber A hangs up histelephone-receiver the circuit oi' battery rthrough the windings of relay t is opened at the substation and thecontacts m and 13 are permitted to close together, thereby closingcircuit through lamp m. In the same manner the subscriber Bin hanging uphis telephone opens the circuit through relay r, thereby lighting thelamp c. `When the pIugs are returned to their seats, the lamp-circuitsare opened at the contacts of the plug-seat switches. If one of thesubscribers should desire an immediate reconnection with anothersubscriber, he may by vibrating his switch-hook in the usual -mannercause the lamp to be alternately lighted and extinguished to thus conveythe signal to the operator for reconnection.

I disclaim herein. the matter claimed in the patent to Francis W. Dunbarfor telephoneswitchboard systems, No. 686,272, dated August 12, 1901.

Having described my invention, what I claim as new, and desire to secureby Letters Patent, is

1. The combination with a pair of telephone-lines, of arepeating-coilthrou gh which the same are adapted to be united forconversation, a signal -controlling electromagnet bridged between thetwo limbs of the talking-circuit of each of said lines, a source ofelectricity adapted to be connected in circuit with said electromagnet,and means Jfor preventing the current therefrom from passing through thewinding of the repeating-coil associated therewith, substantially asdescribed.

2. The combination with a pair of telephone-lines, of a repeating-coilthrough which the same are adapted to be united for conversation, asource of electricity and an impedance element bridged between the twolimbs of the talking-circuit ot' one of said lines, like partsassociated with the other line, and means for preventing the currentfrom said source or sources from passing through the winding' of therepeating-coil associated therewith, sub stantially as described. i

4. rI`he combination with a pair of telephone-lines of a repeating-coilthrough which the same are adapted to be united for conversation, asignal-controlling electromagnet and a charging source of electricitybridgedv between the two limbs of the talking-circuit of each of saidlines, a switch at each substation 'for controlling the passage ofcurrent through the signal-controlling electromagnet connectedtherewith,'and Va condenser interposed in the circuit of each of thewindings of said repeating-coil to prevent the passage of the currentfrom said source through said windings, substantially as described. A

5. The combination with a pair of telephone-lines, ofa repeating-coilthrough which the same are adapted to be united for conversation, asignal-'controlling electromagnet and a source of electricity bridgedbetween the two limbs of the talking-circuit of both of said lines, andmeans for preventing the winding of the repeating-coil fromshort-circuiting said source of electricity, substantially as described.

6. The combination with a pair of telephone-lines, oi' a repeating-coilto connect said lines for conversation, a pair of circuit-controllingelectromagnets, one connected in parallel with each winding of saidrepeating-coil, means for sending charging-currents through saidelectromagnets, a switch at each substation for controlling the circuitthrough the electromagnet corresponding to said line, supervisorysignals controlled by the electromagnets and means for renderingV thewindings ot' said repeating-coil opaque to the passage of thecharging-currents, substantially as described. v

7. The combination with a pair ot' telephone-lines, of a repeating-coilto connect said lines for conversation, a pair of signal-controllingelectromagnets bridged across the circuit one on` either side of therepeatingcoil, means for sending chargingcurrent through saidelectromagnets, a switch at each substation controlling' the circuitthrough the electromagnet corresponding' to that line, a supervisorysignal controlled by each magnet and a condenser in circuit with eachrepeating-coil winding to render the same opaque to the passage ofcharging-currents,substantially as described.

8. The combination with a cord connector -terminating inconnecting-plugs, of a repeating-coil interposed between said plugs, apair -of signal-controlling electromagnets, one in parallel with eachwinding of said repeatingcoil, means for sending charglng-currentsthrough the windings of said electromagnets,

- condensers in the path of current through said repeating-coil windingsto render the same opaque to the passage of said charging-currents, aplug-seat switch for each of said plugs, and a pair of supervisorysignals for the cord connector, one controlled by one of Vsaidelectromagnets and corresponding plugseat switch, and the othercontrolled by the Aother electromagnet and the corresponding plug-seatswitch, substantially as described.

9. Thecombination withapairof telephonelines, of a cord-circuit toconnect said lines for conversation, a repeating-coil in the cordcircuitto inductively unite its two ends, a pair of signal-controllingelectromagnets, one connected in parallel with each winding of saidrepeating-coil, means for sending a continuous current through saidelectromagnets,

a switch at each substation for controlling the circuit through thecorresponding electromagnet, supervisory signals controlled by saidelectromagnets, and means Jfor rendering the windings of' saidrepeating-coil opaque to the passage of charging-currents, substantiallyas described.

l0.- The combination with a pair of telephone-lines, of a cord-circuitto connect said lines for conversation, a repeating-coil in thecord-circuit to inductively unite its two ends,

a pair of signal-controlling electromagnets, one connected in parallelwith each winding of said repeating-coil, means for sending a continuouscurrent through said electromagnets, a switch at each substation forcontrolling the circuitthrough the corresponding electromagnet, and acondenser in circuit with each winding of said repeating-coil to renderthe same opaque to the charging-currents, substantially as described.

11. rlhe combination with a pair of telephone-lines, ot' a cord-circuitto connect said substantially as described.

12. The combination with a pair of telephone-lines, of a cord-circuit toconnect said lines for conversation, a repeating-coil inductivelyconnecting the two ends of the cordcircuit, a pair of signal-controllingelectromagnets connected with the cord-circuit, one in paralled witheach winding of said repeating-coil, a separate source of current forsending current through each said electromagnet, a switch at eachsubstation forcontrolling the circuit through the electromagnet andsource corresponding to said line, and a condenser for rendering thewindings of said repeatingcoil opaque to the passage ofcharging-currents, substantially as described.

13. The combination with two telephonelines, of a repeating-coil tounite said lines for conversation, a condenser in the circuit of eachwinding of said repeating-coil, and a charging source of electricity andan impedance element bridged between the limbs of each of the connectedtelephone-lines, substantially as described.

lli. rlhe combination with two telephonelines, of a repeating-coil tounite said lines for conversation, and a charging source of electricityand a signal-controlling .electromagnet bridged between the limbs ofeach ofthe connected telephone-lines, said repeating-coil windings beingopaque to current from said source, substantially as described.

l5. The combination with a pair of telephone-lines, of a cord-circuitterminating in connecting-plugs to connect said lines for conversation,a repeating-coil in the cord-circuit to inductively unite its two ends,a pair of signal-controlling electromagnets one connected in parallelwith each winding of said repeating-coil, means for sending a continuouscurrent through said electromagnets, a switch at each substation forcontrolling the circuit through the corresponding electromagnet, meansto render the windings of said repeating-coil opaque to the passage ofcharging-current, a plug-seat switch for each of the plugs, and a pairof supervisory signals for the cord-circuit, one signal controlled byone of the electromagnets and corresponding plug-seat switch and theother signal controlled by the other electromagnet and the correspondingplug-seat switch, substantially as described.

16. The combination with a pair of telephone-lines, of a cord-circuit toconnect said lines for conversation, a connecting-plug for each end ofthe cord-circuit, a repeating-coil inductively connecting the two endsof the cord-circuit, a pair of signal-controlling electromagnetsconnected with the cord-circuit one in parallel with each winding ofsaid repeating-coil, a separate source ot' current Jfor sending currentthrough each of said electromagnets, a switch at each substation forcontrolling the circuit through the electromagnets and sourcecorresponding to said line, means for rendering the windings of saidrepeating-coil opaque to the passage of charging-current, a plug-seatswitch for each of the plugs, and a supervisory signal for each end ofthe cord-circuit controlled by the corresponding plug-seat switch andelectromagnet, substantially as described.

17. The combination with a pair of telephone-lines, of a cord-circuitterminating in connecting-plugs to connect said lines for conversation`a repeating-coil in the cord-circuit to inductively unite its two ends,a pair of signal-controlling electromagnets one connected in parallelwith each winding of said repeating-coil, means for sending a continuouscurrent through said electromagnets, a switch at each substation forcontrolling the circuit through the corresponding electromagnet, meansto render the windings of said repeating-coil opaque to the passage ofcharging-current, a pair of supervisory signals for the cord-circuitoperated over local circuits controlled at one point by the saidelectromagnets so as to render the said signals inert when the magnetsare energized, and other means to complete said local circuit at anotherpoint when connections are established with the lines for conversationand to open' them w hen the connecting-plu gs are not in use,substantially as described.

18. The combination with a pair of telephone-lines, of a cord-circuit toconnect said lines for conversation, a repeating-coilin the cord-circuitto inductively unite its two ends, a pair of signal-controllingelectromagnets, one connected in parallel with each winding of saidrepeating-coil, means for sending a continuous current through saidelectromagnets, a switch at each substation for controlling the circuitthrough the corresponding electromagnet, a plug-seat switch for each endof the cord-circuit, and a signal for each end of the cord-circuitcontrolled by the associated magnets and plug-seatswitches,substantially as described.

19. The combination with a pair of telephone-lines, of a cord-circuit toconnect said lines for conversation, a repeating-coil inductivelyconnecting the two ends of the cord-circuit, a pair oi'signal-controlling electromagnets connected with the cord-circuit, onein parallel with each winding of said repeatingcoil, a separate sourceof current for sending current through each said electroinagnet, and aswitch at each substation for controlling the circuit through theelectromagn'et and source corresponding to said line, substantially asdescribed.

20. The combination with a pair of telephone-lines, of a cord-circuit toconnect said lines for conversation, a repeating-coil inductivelyconnecting' the two ends of the cord-circuit, a pair ofsignal-controlling electromagnets connected with the cord-circuit, onein parallel with each winding o't' said repeatingcoil, a separate sourceof current for-sending current through each said electromagnet, and aswitch at each substation for controlling the circuit through theelectromagnet and source corresponding to said line, substantially asdescribed.

21. The combination with two telephonelines,of acord-circuit to unitesaid lines for conversation, the ends of said cord-circuit beingseparated by an inductive device, and a separate charging source ofelectricity and an impedance element bridged between the strands of eachend of a cord-circuit whereby current is independently supplied to eachline for talking. substantially as described.

22. The combination with two telephonelines, of a cord-circuit toconnect said lines together for conversation, a repeating-coilinductively joining the two ends of the cord-circuit, and a separatecharging source of electricity and an impedance element bridged betweenthe limbs of each end of the cord-circuit, substantially as described.

23. The combination with two telephonelines, of a repeating-coil tounite said lines for conversation, a charging source of electricity andasignal-controlling electromagnet bridged between the limbs of each of`the connected telephone-lines, a plug-seat switch for each end of thecord-circuit, and supervisory signals controlled by said switches andelectromagnets, substantially as described.

24. The combination with two telephonelines, of an inductive device tounite said lines for conversation, a charging source of electricity anda signal-controlling electromagnet bridged between the limbs of each ofthe connected telephone-lines, a plug-seat switch for eachconnecting-plug, and a signal associated with each line duringconversation and controlled by the joint action of said plug-seat switch`and said signal-controlling electromagnet, substantially as described.

25. The combination with a pair of telephone-lines, of a cord-circuit toconnect said lines for conversation, a repeating-coil to inductivelyunite the two ends of the cord-circuit, apair of signal-controllingelectromagnets bridged across the cord-circuit one on either side of therepeating-coil, means for sending charging-current through saidelectromagnets, and a switch at each. substation controlling `thecircuit through the electromagnet corresponding to that line,substantially as described.

26. The combination with a cord connector terminating inconnecting-plugs, of a repeating-coil interposed between said plugs, apair of signal-controlling electromagnets` one in parallel with eachwinding of said repeatingcoil, means for sending charging-currentsthrough the windings of said electromagnets during conversation, aplug-seat switch for each of said plugs, and a pair of signaling devicesone controlled by one of said electromagnets and corresponding plug-seatswitch and the othercontrolled by the other electromagnet and thecorresponding plug-seat switch, said seats being arranged when the plugsare placed therein to prevent the display of said signals and at othertimes to permit the display thereof, substantially as described.

27. The combination with the telephoneylines of a telephone-exchange, ofa cord-circuit to unite said lines for conversation, a repeating-coilinterposed in the cord-circuit to conductively separate and inductivelyunite the two ends of the cord-circuit, a charging source of electricityand an impedance element included in a bridge separate from therepeating-coil and between the limbs of each end of the cord-circuit,substantially as described.

28. The combination with a cord'connector terminating inconnecting-plugs, ol" a repeating-coil interposed between said plugs, apair of signal-controlling electromagnets, one in parallel with eachwinding of said repeatingcoil, means for sending charging-currentsthrough the windings of said electromagnets during conversation, aplug-seat switch for each of said plugs, and a pair of supervisorysignals for the cord connector, one signal controlled by one of saidelectromagnets and corresponding plug-seat switch` and the other signalcontrolled by the other electromagnet and the corresponding plug-seatswitch, said plug-seat switches being arranged when the plugs are placedtherein to prevent the display of the signals, substantially asdescribed.

29. rl`he combination with a pair of telephone-lines, of a cord-circuitto unite said lines for conversation, the ends of said cordcircuit beinginductively united, a source of current and an electromagnet bridgedacross each end of the cord-'circuit independent of the inductive devicewhereby current is supplied t'rom the central oiiice to thesubstationlines for conversation, and supervisory signals controlled bythe said magnets during conversation, substantially as described.

30. The combination with a pair of telephone-lines, of a cord-circuit tounite said lines for conversation, the ends of said circuit beinginductively united, an electromagnet connected across each end of thecord-circuit and having divided windings, a source of current interposedbetween the windings of each magnet to furnish current over thecorresponding telephoneline for conversational purposes, and supervisorysignals for the cord-circuit controlled by said magnets duringconversation, substantially as described.

31. The combination with a pair of telephone-lines, oi a cord-circuit tounite said lines for conversation, the ends of the cordcircuit beinginductively united, a separate source of current and an electromagnetbridged across each end of the cord-circuit wherebiT current is suppliedfrom central oi'- iice to each of the substations of the lines fortalking, a supervisory signal for each end of the cord-circuitcontrolled by the corresponding electromagnet to render the sameinoperati ve during conversation, and operative during a connection andwhen the subscribers telephone is o' its hook, substantially asdescribed.

32. The combination with a pair of telephone-lines, of a cord-circuit tounite said lines for conversation, the ends of the cordcircuit beinginductively united, a source ot' current and an electromagnet bridgedacross each end of the cord-circuit whereby current is supplied Jfromthe central office to the substation of the lines for talking, asupervisory signal for each end of the cord-circuit, the circuit of saidsignals being provided with current by auxiliary means when connectionis established and the subscribers telephones are not in use anddeprived of operating-current during conversation by the said magnets,substantially as described. l

A33. The combination with a pair of telephone-lines, of a cord-circuitto unite said lines for conversation, the ends of the cordcircuit beinginductively united, a source of current and an electromagnet bridgedacross each end of the cord-circuit whereby current is supplied from thecentral ofiice to the substation of the lines talking, a supervisorysignal for each end of the cord-circuit, the circuits of said signalsbeing controlled at one point by the said magnets and at another pointby auxiliary means, substantially as described.

34. The combination with a pair of telephone-lines, of a cord-circuit tounite said lines for conversation, the ends ot' the cordcircuit beinginductively united, a source of current and an electromagnet bridgedacross each end of the cord-circuit whereby current is suppliedvfrom thecentral oice to the substation of the lines for talking, as'upervisorysignal for each end oi' the cord-circuit, each said signal having anindependent operatingcircuit controlled at one point by thecorresponding relay and at another point by auxiliary means so that thesaid circuits are completed during connections and. opened under normalconditions, substantially as described.

In witness whereof I have hereunto subscribed my name in the presence oftwo witnesses.

KEMPSTER B. MILLER. Witnesses:

M. R. RooKFoRD, M. R. NYMAN.

